In-mold Labels

By Jack Kenny | October 11, 2010

A small niche in the label industry, in-mold is forecast to enjoy steady growth over the next five years.

Multi-Color Corporation won a first place award
in the 2008 Packaging & Label Gravure Association's annual competition with these paper in-mold labels for Prestone.
Although it occupies a minuscule slice of the global label market – 2 percent in 2009 – in-mold labeling enjoyed growth of 3.3 percent last year, second only to the 4.4 percent experienced by the popular shrink sleeve segment. And that growth is forecast to continue steadily over the next five years, according to AWA Alexander Watson Associates, which studies label markets and trends.

In-mold labels (IML) are in common use among some household products and food packaging, and have been for decades. Still, the market is small in comparison with other label segments, but it appears to be holding its own. In-mold labels have a distinct advantage over other types of labels in that they require no release liner, nor are they applied with adhesives on a separate application line. They are, in fact, molded into place during the manufacture of the container, using a couple of different methods.
Production of in-mold labels is strongest in Europe and in North America. AWA reports that Europe produced 48 percent of all in-mold labels in 2009, and that North America was next with 31 percent. Following were Asia Pacific with 16 percent, and South America with 4 percent. South America, however, had the most significant increase in IML production (6.5 percent) over 2008-2009. Europe was next at 4.5 percent, and Asia Pacific third with just over 3 percent. North America's IML market grew at only 1 percent over that period.

Growth overall for in-mold label production has slowed from a stronger position a decade ago. Around seven or eight years ago, RBS Technologies President Ron Schultz, an IML consultant, noted what he referred to as recisions in the marketplace. A few major in-mold label users – among them SC Johnson and Procter & Gamble – had begun switching some products to pressure sensitive labels.

This series of injection molded labels won an award
last year from the In-Mold Decorating Association.
Here was a direct effect of the expansion of short run labels. From an economic perspective, in-mold labels are best suited to long runs. (And for that reason, rotogravure is a popular printing method for IML.) In addition, setting up an IML machine – the line in which the finished labels are set for placement into the container mold – is a time consuming and costly process that cannot easily bear the rigors of short run changovers. The longer the run, both of the labels and the container manufacturing, the better the economics.

Nonetheless, the shorter run has invaded the IML space. Pay a visit to the grocery store and gaze upon the Tide laundry detergents. The number of SKUs is dizzying. These are in-mold labels. Volumes for these and related products are still high, which makes economic sense, but the label converters and the brand owners have had to retool to accommodate the shorter runs.

What is it?
In-mold labels are printed on paper as well as films, though film products – which must be resistant to certain levels of heat – are more popular. Inks are applied in the customary manner, and are protected on the surface with a top coat that can be solvent or water based, or UV or EB cured. The inks used in the process must have a high degree of abrasion resistance and better than average heat resistance to endure the molding process. UV inks and coatings tend to be used for IML because they offer the requisite protection.

Labels that are applied to containers made using the extrusion blow molding process receive a heat-activated adhesive on the reverse side; this adhesive is activated during the molding process. Containers that are made using the injection molding process are polypropylene, as are the labels. The high temperature and pressure that occur during the molding causes the label to fuse to the container without the help of an adhesive.

The diecutting process differs depending on how the labels are produced. Those printed on rollfed presses are diecut inline with a rotary die. They are then stacked and bundled for the molding process. Labels that are printed in sheets are stacked and run through a unit called a high diecutter. In this process, stacks of rough-cut labels are rammed through a tunnel in a specially crafted machine and emerge cut to size.

At the container manufacturing plant, the labels are placed into magazines, from which they will be removed one by one and placed into the container mold. They are held in place either by static charge or vacuum. Then the mold is closed and the molten plastic is introduced into the mold. It is at this point that the heat from the plastic activates the adhesive on the label, resulting in adherence to the container. Now the label is molded to the wall of the container, and has become a part of it.

The labels can be printed, of course, using any of several printing processes, including flexo, gravure, offset, screen, or digital. Because electrostatic charges are used in many in-mold processes, caution must be taken to exclude the use of foils and conductive inks and coatings in the manufacture of the labels. The charge has to be strong enough to keep the label in place during the molding process, but too strong a charge can polarize the label, causing problems with adherence to the container. Humidity is also a factor to be considered during the IML process.

Incorporation into the container offers the label a form of protection that some of its counterparts don't share. IML labels are resistant to scuffing, weather, water, oils and grease, and a variety of other compounds.

The labels on a container of Lloyd's Barbecue, a Hormel Foods product, won a first place award this year for Best Thin Wall Packaging from the In-Mold Decorating Association.
Two types of container molding dominate the IML landscape: extrusion blow molding and injection molding. In North America, blow molding predominates at about 81 percent of all IML production. (That's considerably lower than the 95 percent reported nearly a decade ago.) Most of the IML products in Europe — about 94 percent — are formed through the injection molding process.

The blow molding process is typically used for bottles, which generally hold such liquids as laundry detergents, personal care products and juices. Containers that are made in the injection molding process are mostly open-top tubs. In Europe, these hold dairy foods in one form or another, such as cheeses, margarines and sauces, and they can command the somewhat higher cost of IML because they are considered to be specialty products. In North America, dairy products are thought of as commodities, and package decoration tends not to be expensive.

The injection molding process permits the creation of containers with in-mold labels covering many, if not all, sides of the tub, as well as those in-the-round.

After the printed labels are cut and stacked, the converter runs a series of tests on the label and records its performance. These include ink rub, substrate thickness testing, gloss metering, color measurement, and heat seal testing, which simulates what takes place during the blow molding process.

The creation of the in-mold labeling process was the brain child of Procter & Gamble back in the 1970s. The consumer products company joined forces with Owens Illinois, the packaging and container company, and with Multi-Color Corporation, the Ohio based label printer, to develop an extrusion blow molded container with the label incorporated into the structure. The result, of course, was a success, and a new product decoration method was born.

This in-mold label by Multi-Color Corporation won a first place award from TLMI in 2008 in the offset color process prime category.
Multi-Color is still active in the IML marketplace. In early 2005, Multi-Color acquired NorthStar Print Group, based in Wisconsin, another major in-mold label producer.

Just last month the In-mold Decorating Association, composed of those converters who manufacture the labels, participated in the 2010 In-mold Labeling and Decorating Conference in Miami, FL, USA, which is produced by AWA. The event had 120 attendees, down a bit from its peak attendance a few years back, but encouraging as businesses climb out of a global recession, says Corey Reardon, AWA's president.

William Llewellyn, vice president and senior consultant for AWA, spoke to the assembly about trends in the IML marketplace. "IML growth held up well through the economic winter of 2008-2009," he said. "Food applications remain a mainstay of the IML marketplace." The potential for growth remains high for the injection molding process and its products, he added, and said that IML "remains a 'bijou' label format."

In-mold labeling is not without its challenges, however. There are ever-increasing cost pressures, Llewellyn said, and the constant increase of brand fragmentation. Moreover, the IML industry always faces competition from alternative product decoration formats; sleeve labels is one such challenger.
Still, he notes, growth is occurring in the market for larger containers, and ink technologies are improving. Also, a third method of container creation – thermoforming – is having somewhat of a resurgence of interest within the IML community.
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